<!DOCTYPE html>
<html lang="en">
<head>
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    <title>Document</title>
    <style>
        div {
            width: 100px;
            height: 100px;
            background-color: orange;
            transition: all 1s;
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    </style>
</head>
<body>
    <div id="div"></div>

    <script>
        div.addEventListener('transitionend', (e) => {
            console.log(e)
        })

        setTimeout(() => {
            div.style.height = '200px'
        }, 2000)
    </script>
</body>
</html>